A digital technology expert is backing the Government's moves to make the use of the Covid Tracer app mandatory in certain circumstances.

Ministry of Health data shows fewer than one in six of the 2.3 million registered app users are using it daily.

Minister for the Covid-19 response Chris Hipkins is looking at whether people should be required to scan in with the app at big events and in places like bars and restaurants, where physical distancing is difficult.

University of Auckland Centre for Informed Futures research fellow Andrew Chen said it was likely people had become complacent about app use, either because they believed they were at low risk of getting Covid-19, or they found the app tricky or annoying to use.

But he said total daily scans needed to get back up to the 2.5 million mark - levels seen in the midst of the Auckland August outbreak.

"That shows what is possible and we need to be getting back up to those sorts of levels to have confidence that enough of the population is covered, so if we send out an exposure notification, we have reasonable confidence that the right people will be notified of a potential exposure."

Businesses also had a role to play in ensuring their QR codes were easily accessible, Chen said.

"There have been a lot of reports that businesses have been strictly speaking complying with the requirement of displaying a QR code, but having it in a place that's annoying to get to, or is hidden or is otherwise obscured."

The app's key advantage, Chen said, was speed.

"I believe that the manual contact tracing system is good and that given enough time, we can find all of the contacts that we need to find.

"But one of the strongest factors that influences the spread of the disease is speed of response and if we can use the app, we might be able to give instructions to people who may have been exposed to Covid-19 more quickly.

"If they can isolate themselves more quickly, then they can reduce the spread of the disease and potentially save lives."

However, Chen said the Government needed to be mindful of people who were not able to use the app.

"I do think that we have to be careful in terms of understanding that not everybody can use the app and that there has to be other provisions in place for people who cannot or have very legitimate reasons for choosing not to use the app."

Hipkins has said he would be getting more advice in the next few days about how to strengthen the contact tracing system.

Text by Sarah Robson of RNZ